Power conversion device and power conversion method

Abstract

The present invention provides a power conversion device and a power conversion method that enable miniaturization of the device. [Solution] The power conversion device 1 comprises a three-phase motor 3, a primary inverter 5a, a secondary inverter 5b, a mechanical switch 7, gate drive circuits 11a, 11b, and an MCU (control unit) 13. The MCU 13 comprises a motor control unit 106 that controls the rotational speed of the rotor 21 of the three-phase motor 3, and a charge control unit 108 that controls the charging of the DC battery 15 from a single-phase voltage source 17 via the three-phase motor 3. When controlling the rotational speed, the mechanical switch 7 is turned off to activate the motor control unit 106, and when charging the DC battery 15, the mechanical switch 7 is turned on to activate the charge control unit 108.

Description

[Technical Field]

[0001] The present invention relates to a power conversion device and a power conversion method for driving a motor. [Background technology]

[0002] In recent years, electric vehicles and plug-in hybrid electric vehicles have incorporated a motor with a built-in coil, a DC battery that powers the motor, an inverter circuit that drives the motor, and a charging circuit that converts AC power from a commercial power source or the like into DC power to charge the DC battery (see Patent Documents 1-3 below). With such a configuration, motor drive and battery charging are possible. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-123250 [Patent Document 2] Japanese Patent Publication No. 2023-120877 [Patent Document 3] Japanese Patent Publication No. 2024-58666 [Overview of the project] [Problems that the invention aims to solve]

[0004] In the devices described above, a charging circuit is required to convert AC power to DC power and supply it to a DC battery. Therefore, conventional devices tended to be large in size.

[0005] This invention has been made in view of the above problems, and aims to provide a power conversion device and a power conversion method that can be miniaturized. [Means for solving the problem]

[0006] To solve the above problems, a power conversion device according to one embodiment of the present invention includes a three-phase motor having a first coil, a second coil, a third coil, and a rotor; a primary inverter having a first upper switch connected between one end of the first coil and the positive terminal of a DC battery, a first lower switch connected between one end of the first coil and the negative terminal of a DC battery, a second upper switch connected between one end of the second coil and the positive terminal of a DC battery, a second lower switch connected between one end of the second coil and the negative terminal of a DC battery, a third upper switch connected between one end of the third coil and the positive terminal of a DC battery, and a third lower switch connected between one end of the third coil and the negative terminal of a DC battery; a fourth upper switch connected between the other end of the first coil and the positive terminal of a DC battery; and a fourth lower switch connected between the other end of the second coil and the positive terminal of a DC battery. The secondary inverter includes a fifth upper switch connected between the other end of the second coil and the negative terminal of the DC battery, a sixth upper switch connected between the other end of the third coil and the positive terminal of the DC battery, and a sixth lower switch connected between the other end of the third coil and the negative terminal of the DC battery; a changeover switch for turning on and off the connection between one end of the first coil and one end of the third coil and a single-phase voltage source; a drive circuit for controlling the driving of the primary inverter and the secondary inverter; and a control unit for controlling the driving of a three-phase motor via the drive circuit. The control unit includes a motor drive control unit for controlling the rotational speed of the rotor of the three-phase motor, and a battery charge control unit for controlling the charging of the DC battery from the single-phase voltage source via the three-phase motor. When controlling the rotational speed, the changeover switch is turned off to activate the motor drive control unit, and when charging the DC battery, the changeover switch is turned on to activate the battery charge control unit.

[0007] Alternatively, a power conversion method according to another embodiment of the present invention includes a three-phase motor having a first coil, a second coil, a third coil, and a rotor; a primary inverter having a first upper switch connected between one end of the first coil and the positive terminal of a DC battery, a first lower switch connected between one end of the first coil and the negative terminal of a DC battery, a second upper switch connected between one end of the second coil and the positive terminal of a DC battery, a second lower switch connected between one end of the second coil and the negative terminal of a DC battery, a third upper switch connected between one end of the third coil and the positive terminal of a DC battery, and a third lower switch connected between one end of the third coil and the negative terminal of a DC battery; a fourth upper switch connected between the other end of the first coil and the positive terminal of a DC battery, and a second... A power conversion method using a secondary inverter having a fifth upper switch connected between the other end of a coil and the positive terminal of a DC battery, a fifth lower switch connected between the other end of a second coil and the negative terminal of a DC battery, a sixth upper switch connected between the other end of a third coil and the positive terminal of a DC battery, and a sixth lower switch connected between the other end of a third coil and the negative terminal of a DC battery; a changeover switch for turning on and off the connection between one end of a first coil and one end of a third coil and a single-phase voltage source; and a drive circuit for controlling the driving of a primary inverter and a secondary inverter, wherein the drive circuit is used to perform a first control for controlling the rotational speed of the rotor of a three-phase motor, and a second control for controlling the charging of a DC battery from a single-phase voltage source via a three-phase motor, wherein the changeover switch is turned off in the first control and turned on in the second control.

[0008] According to the power conversion device or power conversion method described above, when the control unit controls the rotational speed of the rotor of a three-phase motor, the connection between the single-phase voltage source and the three-phase motor is turned off, and the driving of the primary and secondary inverters is controlled. On the other hand, when the control unit controls the charging of a DC battery, the connection between the single-phase voltage source and the first and third coils of the three-phase motor is turned on, and the driving of the primary and secondary inverters is controlled, thereby charging the DC battery from the single-phase voltage source through the first and third coils. As a result, it becomes possible to boost the input voltage to the DC battery as a DC voltage using the two-phase coils of the motor and the primary and secondary inverters, eliminating the need for a charging circuit for the DC battery. This makes it possible to miniaturize the power conversion device.

[0009] In this embodiment, the battery charging control unit may, when charging the DC battery, stop driving the first upper switch and the first lower switch, connect one end of the first coil to one output of the single-phase voltage source, stop driving the third upper switch and the third lower switch, connect one end of the third coil to the other output of the single-phase voltage source, and control the driving of the fourth upper switch, the fourth lower switch, the sixth upper switch, and the sixth lower switch so that the voltage supplied from the single-phase voltage source to the DC battery becomes the target voltage. In this case, when the control unit controls the charging of the DC battery, the two outputs of the single-phase voltage source are connected to one end of the first coil and one end of the third coil of the three-phase motor, and the driving of the secondary inverter is controlled so that the voltage supplied to the DC battery becomes the target voltage. As a result, stable charging of the DC battery using AC power from the single-phase voltage source is performed.

[0010] Furthermore, the battery charging control unit may, when charging the DC battery, control the driving of the second upper switch, the second lower switch, the fifth upper switch, and the fifth lower switch to control the second coil to absorb pulsating power from the power supplied to the DC battery from the single-phase voltage source. This reduces the pulsating power contained in the power supplied to the DC battery, and allows for a reduction in the capacitance of the capacitor connected to the DC battery. As a result, further miniaturization of the power conversion device becomes possible.

[0011] Furthermore, the battery charging control unit may monitor the input voltage from the single-phase voltage source and control the current in the second coil to be generated at the same frequency as the input voltage but with a phase lag of π / 4 from the phase of the input voltage. In this case, the pulsating power contained in the power supplied to the DC battery can be effectively reduced, and the capacitance of the capacitor connected to the DC battery can be effectively reduced.

[0012] Furthermore, the battery charging control unit may control the amplitude of the current in the second coil so that it is determined based on the inductance of the second coil and the rated power of the DC battery. This effectively reduces the pulsating power contained in the power supplied to the DC battery and effectively reduces the capacitance of the capacitor connected to the DC battery.

[0013] Furthermore, the battery charging control unit may control the operation of the fourth upper switch, the fourth lower switch, the sixth upper switch, and the sixth lower switch so that the currents in the first and third coils become waveforms synchronized with the input voltage from the single-phase voltage source when charging the DC battery. In this case, the power factor of the AC power input from the single-phase voltage source to the three-phase motor can be made close to 1. As a result, the DC battery can be charged efficiently.

[0014] The power conversion device of the embodiment includes [1] a three-phase motor having a first coil, a second coil, a third coil, and a rotor, A primary inverter having: a first upper switch connected between one end of the first coil and the positive terminal of the DC battery; a first lower switch connected between one end of the first coil and the negative terminal of the DC battery; a second upper switch connected between one end of the second coil and the positive terminal of the DC battery; a second lower switch connected between one end of the second coil and the negative terminal of the DC battery; a third upper switch connected between one end of the third coil and the positive terminal of the DC battery; and a third lower switch connected between one end of the third coil and the negative terminal of the DC battery. A secondary inverter having: a fourth upper switch connected between the other end of the first coil and the positive terminal of the DC battery; a fourth lower switch connected between the other end of the first coil and the negative terminal of the DC battery; a fifth upper switch connected between the other end of the second coil and the positive terminal of the DC battery; a fifth lower switch connected between the other end of the second coil and the negative terminal of the DC battery; a sixth upper switch connected between the other end of the third coil and the positive terminal of the DC battery; and a sixth lower switch connected between the other end of the third coil and the negative terminal of the DC battery. A changeover switch for switching the connection between one end of the first coil and one end of the third coil and a single-phase voltage source on and off, A drive circuit that controls the driving of the primary inverter and the secondary inverter, The system includes a control unit that controls the drive of the three-phase motor via the aforementioned drive circuit, The control unit comprises a motor drive control unit that controls the rotational speed of the rotor of the three-phase motor, and a battery charge control unit that controls the charging of the DC battery via the three-phase motor from the single-phase voltage source. When controlling the rotational speed, the changeover switch is turned off to activate the motor drive control unit, and when charging the DC battery, the changeover switch is turned on to activate the battery charge control unit. It is a "power conversion device".

[0015] The power conversion device of the embodiment [2] "When charging the DC battery, the battery charging control unit stops the driving of the first upper switch and the first lower switch, connects one end of the first coil to one output of the single-phase voltage source, stops the driving of the third upper switch and the third lower switch, connects one end of the third coil to the other output of the single-phase voltage source, and controls the driving of the fourth upper switch, the fourth lower switch, the sixth upper switch, and the sixth lower switch so that the voltage supplied from the single-phase voltage source to the DC battery becomes the target voltage." The power converter described in [1] above may also be used.

[0016] The power conversion device of the embodiment [3] "The battery charging control unit controls the driving of the second upper switch, the second lower switch, the fifth upper switch, and the fifth lower switch when charging the DC battery, so that the second coil absorbs pulsating power from the power supplied to the DC battery from the single-phase voltage source, The power converter described in [2] above may also be used.

[0017] The power conversion device of the embodiment [4] "The battery charge control unit monitors the input voltage from the single-phase voltage source and controls the current in the second coil to be generated at the same frequency as the input voltage and with a phase lag of π / 4 from the phase of the input voltage." The power converter described in [3] above may also be used.

[0018] The power conversion device of the embodiment [5] "The battery charging control unit controls the amplitude of the current in the second coil to an amplitude determined based on the inductance of the second coil and the rated power of the DC battery, The power converter described in [3] or [4] above may also be used.

[0019] The power conversion device of the embodiment states: [6] "The battery charging control unit controls the driving of the fourth upper switch, the fourth lower switch, the sixth upper switch, and the sixth lower switch so that when the DC battery is being charged, the currents of the first coil and the third coil have waveforms synchronized with the input voltage from the single-phase voltage source." The power converter described in any of the above [2] to [5] may also be used. [Effects of the Invention]

[0020] According to this disclosure, it is possible to provide a power conversion device and a power conversion method that can be miniaturized. [Brief explanation of the drawing]

[0021] [Figure 1] This figure shows the schematic configuration of the power conversion device 1 according to the embodiment. [Figure 2] Figure 1 is a block diagram showing the functional configuration of MCU13. [Figure 3] This is a timing chart showing the transition states of the drive modes according to the power conversion method of this embodiment. [Figure 4] This figure shows the time waveforms of the six gate signals Su1, Sv1, Sw1, Su2, Sv2, and Sw2 when the power converter 1 is set to motor drive mode. [Figure 5] This figure shows the time waveforms of the six gate signals Su1, Sv1, Sw1, Su2, Sv2, and Sw2 when the power converter 1 is set to battery charging mode. [Figure 6] This graph shows the time variation of the three-phase currents iu, iv, and iw of motor 3 when power converter 1 is set to battery charging mode. [Figure 7] This graph shows the time variation of the supplied power pdc, power consumption pAPD, and input power pbat when the power converter 1 is set to battery charging mode. [Figure 8]This graph shows the simulation results of the time waveforms of various currents and voltages when the power converter 1 is set to battery charging mode. [Modes for carrying out the invention]

[0022] Hereinafter, preferred embodiments of the power conversion device and power conversion method according to the present invention will be described in detail with reference to the drawings. In the description of the drawings, the same or corresponding parts are denoted by the same reference numerals, and redundant descriptions are omitted.

[0023] First, the configuration of the power converter 1 according to the embodiment of this disclosure will be described with reference to Figures 1 and 2. The power converter 1 is a device built into a vehicle such as an electric vehicle or a plug-in hybrid electric vehicle, and has the function of driving a motor as a power source and the function of charging a battery which is the power source for the motor.

[0024] As schematically shown in Figure 1, the power converter 1 comprises a three-phase motor 3, a primary inverter 5a, a secondary inverter 5b, a mechanical switch (changeover switch) 7, a capacitor 9, gate drive circuits 11a and 11b, and a control unit, an MCU (Micro Controller Unit) 13. The power converter 1 is connected to a DC battery 15, which is the power source for the three-phase motor 3, and a single-phase voltage source 17, which is the power source for charging the DC battery 15.

[0025] The three-phase motor 3 has a u-phase coil (first coil) 19u, a v-phase coil (second coil) 19v, a w-phase coil (third coil) 19w, and a rotor 21. The three-phase motor 3 is a drive source that rotates the wheels of a vehicle. The three-phase motor 3 has a u-phase current i flowing through the u-phase coil 19u. u , the v-phase current i flowing through the v-phase coil 19V v , and the w-phase current i flowing through the w-phase coil 19w w Current monitors 23u, 23v, and 23w detect the respective currents, and the angular position θ of the rotor 21. mA position sensor 25 is attached to detect the current. The current monitors 23u, 23v, 23w, and the position sensor 25 are configured to output their respective detected values ​​to the MCU 13.

[0026] The DC battery 15 is a power source that supplies power to the three-phase motor 3, and can be a lithium-ion battery, lead-acid battery, nickel-metal hydride battery, nickel-cadmium battery, or solid-state battery. The DC battery 15 supplies power to the three-phase motor 3 via a smoothing capacitor 9, a primary inverter 5a, and a secondary inverter 5b, which are connected in parallel to each other at both ends of the DC battery 15.

[0027] The primary inverter 5a includes an upper switch (first upper switch) 271 and a lower switch (first lower switch) 272 that connect the u-phase coil 19u to the DC battery 15, an upper switch (second upper switch) 291 and a lower switch (second lower switch) 292 that connect the v-phase coil 19v to the DC battery 15, and an upper switch (third upper switch) 311 and a lower switch (third lower switch) 312 that connect the w-phase coil 19w to the DC battery 15. Each of the switches 271, 272, 291, 292, 311, and 312 has a configuration in which a semiconductor switch such as a MOSFET or IGBT and a freewheeling diode are connected in parallel. The upper switch 271 is connected between one end u1 of the u-phase coil 19u and the positive terminal of the DC battery 15, and the lower switch 272 is connected between one end u1 of the u-phase coil 19u and the negative terminal of the DC battery 15. The upper switch 291 is connected between one end v1 of the v-phase coil 19V and the positive terminal of the DC battery 15, and the lower switch 292 is connected between one end v1 of the v-phase coil 19V and the negative terminal of the DC battery 15. The upper switch 311 is connected between one end w1 of the w-phase coil 19w and the positive terminal of the DC battery 15, and the lower switch 312 is connected between one end w1 of the w-phase coil 19w and the negative terminal of the DC battery 15.

[0028] In the primary inverter 5a with the above configuration, the upper switch 271 and the lower switch 272 are switched complementaryly, allowing for repeated switching of the connection between one end u1 of the u-phase coil 19u and the positive and negative terminals of the DC battery 15. The upper switch 291 and the lower switch 292 are switched complementaryly, allowing for repeated switching of the connection between one end v1 of the v-phase coil 19v and the positive and negative terminals of the DC battery 15. The upper switch 311 and the lower switch 312 are switched complementaryly, allowing for repeated switching of the connection between one end w1 of the w-phase coil 19w and the positive and negative terminals of the DC battery 15.

[0029] The secondary inverter 5b includes an upper switch (fourth upper switch) 331 and a lower switch (fourth lower switch) 332 that connect the u-phase coil 19u to the DC battery 15, an upper switch (fifth upper switch) 351 and a lower switch (fifth lower switch) 352 that connect the v-phase coil 19v to the DC battery 15, and an upper switch (sixth upper switch) 371 and a lower switch (sixth lower switch) 372 that connect the w-phase coil 19w to the DC battery 15. Each of the switches 331, 332, 351, 352, 371, and 372 has a configuration in which a semiconductor switch such as a MOSFET or IGBT and a freewheeling diode are connected in parallel. The upper switch 331 is connected between the other end u2 of the u-phase coil 19u and the positive terminal of the DC battery 15, and the lower switch 332 is connected between the other end u2 of the u-phase coil 19u and the negative terminal of the DC battery 15. The upper switch 351 is connected between the other end v2 of the v-phase coil 19v and the positive terminal of the DC battery 15, and the lower switch 352 is connected between the other end v2 of the v-phase coil 19v and the negative terminal of the DC battery 15. The upper switch 371 is connected between the other end w2 of the w-phase coil 19w and the positive terminal of the DC battery 15, and the lower switch 372 is connected between the other end w2 of the w-phase coil 19w and the negative terminal of the DC battery 15.

[0030] In the secondary inverter 5b of the above configuration, the upper switch 331 and the lower switch 332 are switched complementaryly, allowing for repeated switching of the connection between the other end u2 of the u-phase coil 19u and the positive and negative terminals of the DC battery 15. The upper switch 351 and the lower switch 352 are switched complementaryly, allowing for repeated switching of the connection between the other end v2 of the v-phase coil 19v and the positive and negative terminals of the DC battery 15. The upper switch 371 and the lower switch 372 are switched complementaryly, allowing for repeated switching of the connection between the other end w2 of the w-phase coil 19w and the positive and negative terminals of the DC battery 15. By having such a dual inverter configuration, the power converter 1 is superior in terms of system fault tolerance and motor output.

[0031] The gate drive circuits 11a and 11b are circuits that control the driving of the primary inverter 5a and the secondary inverter 5b. The gate drive circuit 11a generates six square wave voltage signals, which are gate signals, for switching the switches 271, 272, 291, 292, 311, and 312 included in the primary inverter 5a, in response to control by the MCU 13, and applies the six gate signals to each of the switches 271, 272, 291, 292, 311, and 312. The gate drive circuit 11b generates six square wave voltage signals, which are gate signals, for switching the switches 331, 332, 351, 352, 371, and 372 included in the secondary inverter 5b, in response to control by the MCU 13, and applies the six gate signals to each of the switches 331, 332, 351, 352, 371, and 372.

[0032] The mechanical switch 7 is a pair of mechanical switches 7a and 7b that turn on and off the connection between one end u1 of the u-phase coil 19u and one end w1 of the w-phase coil 19w, and a single-phase voltage source 17 such as a commercial power supply outside the power conversion device 1. That is, one output of the single-phase voltage source 17 is connected to one end u1 of the u-phase coil 19u via the mechanical switch 7a, and the other output of the single-phase voltage source 17 is connected to one end w1 of the w-phase coil 19w via the mechanical switch 7b. The mechanical switch 7 receives a drive mode signal (switching control signal) from the MCU 13, and turns on or off the connection between the single-phase voltage source 17 and the u-phase coil 19u and the w-phase coil 19w of the three-phase motor 3 by turning on or off the pair of switches 7a and 7b simultaneously according to the drive mode signal.

[0033] Furthermore, the power conversion device 1 includes two voltage monitors 39 and 41. The voltage monitor 39 detects the AC voltage v output from the single-phase voltage source 17, and outputs the detected value of the voltage v in to the MCU 13. The voltage monitor 41 detects the DC voltage v applied to the DC battery 15, and outputs the detected value of the voltage v in to the MCU 13. dc to the MCU 13. dc

[0034] The MCU (Micro Controller Unit) 13 is a control circuit that controls the drive of the three-phase motor 3 and controls the charging of the DC battery 15. FIG. 2 is a block diagram showing the functional configuration of the MCU 13. The MCU 13 includes an analog / digital (A / D) converter 101, a digital / analog (D / A) converter 102, a three-phase / two-phase conversion unit 103, a motor speed calculation unit 104, a phase detector 105, a motor control unit (motor drive control unit) 106, a signal generation unit 107, a charging control unit (battery charging control unit) 108, a signal generation unit 109, and a soft switch 110.

[0035] The A / D converter 101 converts the u-phase current i u , v-phase current i v , w-phase current i w , angular position θ m , and AC voltage v in, and DC voltage v dc Each of these values ​​is converted from an analog value to a digital value and output. The three-phase / two-phase conversion unit 103 converts the u-phase current i output from the A / D converter 101. u , v phase current i v , and w-phase current i w The value of the d-axis current i d The values ​​of the q-axis current iq and the zero-sequence current i0 are converted and output. The motor speed calculation unit 104 uses the angular position θ continuously output from the A / D converter 101. m Differentiating the value of gives the angular velocity ω of the rotor 21 of the three-phase motor 3. m The phase detector 105 consists of an integrator and a rotational coordinate converter, and the AC voltage v output from the A / D converter 101 is calculated and output. in Based on this value, an AC voltage v is generated using a PLL (Phase Locked Loop). in Phase θ in It estimates and outputs the following.

[0036] The motor control unit 106 is a functional unit for controlling the rotational speed and torque of the rotor 21 of the three-phase motor 3, and includes a motor speed control unit 121, a maximum torque / minimum current control unit 122, a motor current control unit 123, and a two-phase / three-phase conversion unit 124. The motor control unit 106 is activated when it is set to the motor drive mode, which is an operating mode for controlling the rotational speed and torque of the three-phase motor 3. The motor speed control unit 121 uses a proportional-integral controller (PI controller) to control the motor rotor speed command value ω set from an external source. m * And the angular velocity ω of the rotor 21 m The motor torque command value τ such that the deviation from is zero. m * The maximum torque / minimum current control unit 122 calculates the motor torque command value τ. m * Based on this, the d-axis current command value i is determined to generate the maximum torque with the minimum current. d * and q-axis current command value i q * This is calculated using the motor torque formula. The motor current control unit 123 calculates the d-axis current command value id * and q-axis current command value i q * And the zero-sequence current command value i0 is set to zero. * And, d-axis current i d Based on the values ​​of the q-axis current iq and the zero-sequence current i0, the d-axis voltage command value v is set such that the deviation between the command value and the measured value is zero. d * q-axis voltage command value v q * , and zero-sequence voltage command value v0 * The two-phase / three-phase conversion unit 124 calculates the d-axis voltage command value v. d * q-axis voltage command value v q * , and zero-sequence voltage command value v0 * The u-phase voltage command value v u * , v-phase voltage command value v v * , and the w-phase voltage command value v w * Convert and output.

[0037] The charging control unit 108 is a functional unit that controls the charging of the DC battery 15 via the three-phase motor 3 from the single-phase voltage source 17, and includes a voltage control unit 131, a pulsating power compensation unit 132, and a motor current control unit 133. The charging control unit 108 is activated when it is set to battery charging mode, which is an operating mode for controlling the charging of the DC battery 15. The voltage control unit 131 uses a proportional-integral controller (PI controller) to control the DC voltage command value (target voltage) set externally v dc * And the measured value of DC voltage v dc The DC current command value i, which is the target current value supplied to the DC battery 15, is set so that the deviation from this value becomes zero. dc * Calculate the DC current command value i. dc * is an AC voltage v in Phase θ in The value of the sine function in the phase that coincides with this is multiplied by the u-phase current command value i u *This is output as follows: u-phase current i u and w-phase current i w The input voltage v from the single-phase voltage source 17 in The waveform becomes synchronized with the DC voltage v dc The drives of the upper switch 331, lower switch 332, upper switch 371, and lower switch 372 of the secondary inverter 5b are controlled so that the voltage reaches the target voltage (details will be described later).

[0038] The pulsating power compensation unit 132 of the charging control unit 108 includes a compensation current amplitude value calculation unit 134. The compensation current amplitude value calculation unit 134 calculates the rated charging power p of the DC battery 15, which is set externally. c and the inductance L of the V-phase coil 19V v Based on this, the amplitude value I of the v-phase current required to compensate for pulsating power v * The pulsating power compensation unit 132 calculates the AC voltage v, which is the monitored measured value. in Phase θ in The value of the sine function at a phase lag of π / 4 is calculated, and the amplitude value I of the v-phase current is applied to that value. v * Multiply by the v-phase current command value i v * This outputs the voltage v. This controls the operation of the upper switch 291 and lower switch 292 of the primary inverter 5a and the upper switch 351 and lower switch 352 of the secondary inverter 5b so that the pulsating power is absorbed by the v-phase coil 19V (details will be described later). With this function, the pulsating power compensation unit 132 monitors the AC voltage v. in AC voltage v at the same frequency in The v-phase current i is lag by π / 4 from the phase of the first phase. v The v-phase current command value i is such that this occurs. v * It can generate [this].

[0039] The motor current control unit 133 uses a proportional-integral controller (PI controller) to set the u-phase current command value i u * and v-phase current command value i v* and the measured value of the u-phase current i u and the v-phase current i v so that the deviation from the value of becomes zero, the u-phase voltage command value v u * , the v-phase voltage command value v v * , and the w-phase voltage command value v w * are calculated. At this time, the motor current control unit 133 makes the w-phase current I w become the current waveform in which the current waveform of the u-phase current I u is inverted, and the u-phase voltage command value v u * , the v-phase voltage command value v v * , and the w-phase voltage command value v w * are calculated.

[0040] Based on the u-phase voltage command value v u * , the v-phase voltage command value v v * , and the w-phase voltage command value v w * output from the motor control unit 1⃣0⃣6⃣, the signal generation unit 1⃣0⃣7⃣ performs PWM control using the triangular wave comparison method so that the u-phase voltage v u , the v-phase voltage v v , and the w-phase voltage v w approach the command value, and generates the gate signals S u1 , S v1 , Ss w1 for switching the primary side inverter 5a and the gate signals S u2 , S v2 , Ss w2 for switching the secondary side inverter 5b. The gate signal S u1 is a voltage signal for complementarily switching the upper switch 2⃣7⃣1⃣ and the lower switch 2⃣7⃣2⃣, the gate signal S v1 is a voltage signal for complementarily switching the upper switch 2⃣9⃣1⃣ and the lower switch 2⃣9⃣2⃣, and the gate signal S w1 is a voltage signal for complementarily switching the upper switch 3⃣1⃣1⃣ and the lower switch 3⃣1⃣2⃣. Also, the gate signal Su2 This is a voltage signal for complementary switching of the upper switch 331 and the lower switch 332, and is the gate signal S v2 This is a voltage signal for complementary switching of the upper switch 351 and the lower switch 352, and is the gate signal S w2 This is a voltage signal for complementary switching of the upper switch 371 and the lower switch 372.

[0041] Similarly, the signal generation unit 109 receives the u-phase voltage command value v output from the charge control unit 108. u * , v-phase voltage command value v v * , and the w-phase voltage command value v w * Based on this, the u-phase voltage v u , v-phase voltage v v , and the W-phase voltage v w By performing PWM control using a triangular wave comparison method so that the gate signal S for switching the primary inverter 5a approaches the command value, the gate signal S is generated. u1 ,S v1 ,S w1 And the gate signal S for switching the secondary inverter 5b. u2 ,S v2 ,S w2 The signal generation unit 109 generates a gate signal S, unlike the signal generation unit 107, to stop the switching of the upper switch 271 and the lower switch 272. u1 Generate a gate signal S to stop the switching of the upper switch 311 and the lower switch 312. W1 This generates the following: When the mechanical switch 7 is turned on, one end u1 of the u-phase coil 19u and one end w1 of the w-phase coil 19w are connected to one output and the other output of the single-phase voltage source 17, respectively.

[0042] The soft switch 110 receives gate signals S from the signal generation unit 107 and signal generation unit 109 based on the drive mode signal set by command input etc. in the MCU 13. u1 ,S v1 ,Sw1 ,S u2 ,S v2 ,S w2 The system switches between these modes and inputs the signal to the D / A converter 102. The drive mode signal is set to "0" internally in the MCU 13 when motor drive mode is selected, and to "1" when battery charging mode is selected. The soft switch 110 inputs the output of the signal generation unit 107 to the D / A converter 102 when the drive mode signal is "0" (motor drive mode), and inputs the output of the signal generation unit 109 to the D / A converter 102 when the drive mode signal is "1" (battery charging mode). In addition, the soft switch 110 disables (stops) the operation of the charging control unit 108 when the drive mode signal is "0" (motor drive mode), and disables (stops) the operation of the motor control unit 106 when the drive mode signal is "1" (battery charging mode).

[0043] The D / A converter 102 receives the gate signal S u1 ,S v1 ,S w1 ,S u2 ,S v2 ,S w2 The D / A converter 102 converts the digital value to an analog value and outputs it to the gate drive circuits 11a and 11b. This controls the switching of the primary inverter 5a and the secondary inverter 5b. In addition, the D / A converter 102 converts the drive mode signal from a digital value to an analog value and outputs the converted analog value as a switching control signal to the mechanical switch 7. As a result, if the drive mode signal set by the MCU 13 is "0" (motor drive mode), the mechanical switch 7 is turned off, and if the drive mode signal set by the MCU 13 is "1" (battery charging mode), the mechanical switch 7 is turned on.

[0044] Here, the amplitude value I of the v-phase current by the charging control unit 108 v * Let's explain the calculation in detail.

[0045] In this embodiment, the energy W of pulsating power that can be generated toward the DC battery 15 via the u-phase coil 19u and the w-phase coil 19w rip The angular frequency ω of the single-phase voltage source 17 is in , and the rated charging power p of the DC battery 15 c Using the following formula (1);

number

number

number

[0046] Furthermore, the v-phase current command value i by the charging control unit 108 is also v * I will explain in detail the basis for the calculation.

[0047] In this embodiment, power p supplied from the single-phase voltage source 17 to the DC battery 15 via the u-phase coil 19u and the w-phase coil 19w dc This is expressed by the following formula (4);

number

number

number

[0048] Here, the power p is ultimately input to the DC battery 15. bat This is expressed by the following formula (7);

number

number

[0049] Next, with reference to Figure 3, a power conversion method using the power conversion device 1 according to this embodiment will be described. Figure 3 is a timing chart showing the transition states of the drive modes according to the power conversion method of this embodiment.

[0050] In the power converter 1, when the drive mode signal is set to "0" at time t=t0, the operating mode is set to motor drive mode. As a result, the mechanical switch 7 is turned off, the connection between the single-phase voltage source 17 and the three-phase motor 3 is turned off, and the motor control unit 106 of the MCU 13 is activated, and PWM control at a predetermined switching frequency (e.g., 20kHz) is performed, thereby controlling the rotational speed and torque of the three-phase motor 3 via the gate drive circuits 11a and 11b (first control). Subsequently, when the motor drive mode is stopped at time t=t1, the PWM control is stopped and the drive of the three-phase motor 3 is stopped.

[0051] Next, when the drive mode signal is set to "1" at time t=t2, the operating mode is set to battery charging mode. As a result, the mechanical switch 7 is turned on, the connection between the single-phase voltage source 17 and the three-phase motor 3 is turned on, and the function of the charging control unit 108 of the MCU 13 is activated, and PWM control at a predetermined switching frequency (e.g., 20kHz) is executed, thereby controlling the charging of the DC battery 15 from the single-phase voltage source 17 through the three-phase motor 3 via the gate drive circuits 11a and 11b (second control). Subsequently, when the battery charging mode is stopped at time t=t3, the PWM control is stopped and the charging of the DC battery 15 is stopped.

[0052] Figure 4 shows the six gate signals S when the power converter 1 is set to motor drive mode. u1 ,S v1 ,S w1 ,S u2 ,S v2 ,S w2 The time waveform is shown. As shown in Figure 4, when set to motor drive mode, the six gate signals S are controlled by PWM control. u1 ,S v1 ,S w1 ,Su2 ,S v2 ,S w2 The pulse width is controlled.

[0053] Figure 5 shows the six gate signals S when the power converter 1 is set to battery charging mode. u1 ,S v1 ,S w1 ,S u2 ,S v2 ,S w2 The time waveform is shown. As shown in Figure 5, when set to battery charging mode, the gate signal S u1 and gate signal S w1 The voltage is fixed at zero, and four gate signals S are controlled by PWM. v1 ,S u2 ,S v2 ,S w2 The pulse width is controlled.

[0054] Figure 6 shows the three-phase current i of the three-phase motor 3 when the power converter 1 is set to battery charging mode. u ,i v ,i w This graph shows the time evolution of [the variable]. In Figure 6, the horizontal axis represents the AC voltage V. in Phase θ in This represents the u-phase current i u AC voltage V in Phase θ in The waveform matches, and the w-phase current i u AC voltage V in The waveform is inverted relative to the v-phase current i v AC voltage V in Phase θ in The resulting waveform has a phase delay of π / 4.

[0055] Figure 7 shows the power supply p when the power converter 1 is set to battery charging mode. dc , power consumption p APD , and input power p bat This graph shows the time evolution of [the variable]. In Figure 7, the horizontal axis represents the AC voltage V. in Phase θ inThis represents the power consumption p APD is the power supply p dc The pulsating component oscillates in the same phase and frequency as the input power p. bat Power supply p dc As a result of being able to remove the pulsating component, the input power p bat The pulsation component in this region is reduced. Note that the supplied power p dc The amplitude is 2 × rated charging power p c , power consumption p APD The amplitude is p c (Rated charging power) is set.

[0056] Figure 8 shows the AC voltage v when the power converter 1 is set to battery charging mode. in , input current i in DC voltage v dc , and three-phase current i u ,i v ,i w The simulation results of the time waveform are shown. Here, control by the MCU 13 starts at time t=0.1 sec after the power of the power converter 1 is turned on, and then at time t=0.3 sec, the charge control unit 108 starts rated load operation (u-phase current i u and w-phase current i w The control of the pulsating power is initiated, and at time t=1.0sec, the pulsating power compensation operation by the pulsating power compensation unit 132 (v-phase current i v It is assumed that the control of the u-phase current i has started. Thus, when rated load operation starts, the u-phase current i u and w-phase current i w AC voltage v in As a result of rising in sync with this, the AC voltage v in The input current i flows in from the single-phase voltage source 17, which has a waveform in the same phase as the input current i. in This occurs. At the same time, when rated load operation begins, a DC voltage v dc The DC voltage command value (target voltage) v dc * After it has risen to this point, when the pulsating power compensation operation starts, the AC voltage v in The v-phase current i at the same frequency v As a result of this, the DC voltage v dcAC voltage v included in This suppresses pulsating voltages at twice the frequency.

[0057] The effects and benefits of the power conversion device 1 and the power conversion method using it, as described above, will now be explained.

[0058] According to the power conversion device 1 or power conversion method using the same in this embodiment, when the MCU 13 controls the rotational speed of the rotor 21 of the three-phase motor 3, the connection between the single-phase voltage source 17 and the three-phase motor 3 is turned off, and the drive of the primary inverter 5a and the secondary inverter 5b is controlled. On the other hand, when the MCU 13 controls the charging of the DC battery 15, the connection between the single-phase voltage source 17 and the u-phase coil 19u and w-phase coil 19w of the three-phase motor 3 is turned on, and the drive of the primary inverter 5a and the secondary inverter 5b is controlled, thereby charging of the DC battery 15 from the single-phase voltage source 17 via the u-phase coil 19u and w-phase coil 19w. As a result, it becomes possible to boost the input voltage to the DC battery 15 into a DC voltage using the two-phase coils 19u and 19w of the three-phase motor 3, and the primary inverter 5a and secondary inverter 5b, eliminating the need for semiconductor components and passive components as a charging circuit for charging the DC battery 15. This makes it possible to miniaturize the power converter 1.

[0059] In this embodiment, when charging the DC battery, the charging control unit 108 stops the operation of the upper switch 271 and the lower switch 272, connects one end u1 of the u-phase coil 19u to one output of the single-phase voltage source 17, stops the operation of the upper switch 311 and the lower switch 312, connects one end w1 of the w-phase coil 19w to the other output of the single-phase voltage source 17, and controls the operation of the upper switch 331, the lower switch 332, the upper switch 371, and the lower switch 372 so that the voltage supplied from the single-phase voltage source 17 to the DC battery 15 becomes the target voltage. In this case, when the MCU 13 controls the charging of the DC battery 15, the two outputs of the single-phase voltage source 17 are connected to one end u1 of the u-phase coil 19u and one end w1 of the w-phase coil 19w of the three-phase motor 3, and the operation of the secondary inverter 5b is controlled so that the voltage supplied to the DC battery 15 becomes the target voltage. This ensures that the DC battery 15 is charged stably using AC power from the single-phase voltage source 17.

[0060] Furthermore, when charging the DC battery 15, the charging control unit 108 controls the operation of the upper switch 291, lower switch 292, upper switch 351, and lower switch 352 to absorb pulsating power from the power supplied to the DC battery 15 from the single-phase voltage source 17 at the v-phase coil 19V. This reduces the pulsating power contained in the power supplied to the DC battery 15, and allows for a reduction in the capacitance of the capacitor 9 connected to the DC battery 15. As a result, further miniaturization of the power converter 1 becomes possible.

[0061] Furthermore, the charging control unit 108 receives the AC voltage v from the single-phase voltage source 17. in Monitor the AC voltage v in AC voltage v at the same frequency in The current in the v-phase coil 19V is controlled to be generated with a phase lag of π / 4 from the phase of the current. In this case, the pulsating power contained in the power supplied to the DC battery 15 can be effectively reduced, and the capacitance of the capacitor 9 connected to the DC battery 15 can be effectively reduced.

[0062] Furthermore, the charging control unit 108 controls the v-phase current i of the v-phase coil 19V. v The amplitude is controlled to be the amplitude determined based on the inductance of the V-phase coil 19V and the rated power of the DC battery 15. This effectively reduces the pulsating power contained in the power supplied to the DC battery 15 and effectively reduces the capacitance of the capacitor 9 connected to the DC battery 15.

[0063] Furthermore, when charging the DC battery 15, the charging control unit 108 controls the current i of the u-phase coil 19u and the w-phase coil 19w. u ,i w However, the AC voltage v from the single-phase voltage source 17 in The drives of the upper switch 331, lower switch 332, upper switch 371, and lower switch 372 are controlled so that the waveform is synchronized. In this case, the power factor of the AC power input from the single-phase voltage source 17 to the three-phase motor 3 can be made close to 1. As a result, the power supply harmonic regulation stipulated by JIS or IEC standards can be satisfied. In addition, the DC battery 15 can be charged efficiently.

[0064] The present invention is not limited to the embodiments described above. The configurations of the above embodiments can be modified in various ways. [Explanation of symbols]

[0065] 1…Power converter, 3…Three-phase motor, 5a…Primary inverter, 5b…Secondary inverter, 7…Mechanical switch (changeover switch), 15…DC battery, 17…Single-phase voltage source, 19u…First coil, 19v…Second coil, 19w…Third coil, 21…Rotor, 271…Upper switch (First upper switch), 272…Lower switch (First lower switch), 291…Upper switch (Second upper switch), 292…Lower switch (Second lower switch), 311…Upper switch (Third upper switch), 312…Lower switch (Third lower switch), 331…Upper switch (Fourth upper switch), 332…Lower switch (Fourth lower switch) 351... Upper switch (5th upper switch), 352... Lower switch (5th lower switch), 371... Upper switch (6th upper switch), 372... Lower switch (6th lower switch), 106... Motor control unit (motor drive control unit), 108... Charging control unit (battery charging control unit), i u ,i w …Current, L v ...Inductance, u1, v1, w1...one end, u2, v2, w2...other end, v dc ,v in ...voltage, v in ...input voltage, θ in …phase.

Claims

1. A three-phase motor having a first coil, a second coil, a third coil, and a rotor, A primary inverter having: a first upper switch connected between one end of the first coil and the positive terminal of the DC battery; a first lower switch connected between one end of the first coil and the negative terminal of the DC battery; a second upper switch connected between one end of the second coil and the positive terminal of the DC battery; a second lower switch connected between one end of the second coil and the negative terminal of the DC battery; a third upper switch connected between one end of the third coil and the positive terminal of the DC battery; and a third lower switch connected between one end of the third coil and the negative terminal of the DC battery. A secondary inverter having: a fourth upper switch connected between the other end of the first coil and the positive terminal of the DC battery; a fourth lower switch connected between the other end of the first coil and the negative terminal of the DC battery; a fifth upper switch connected between the other end of the second coil and the positive terminal of the DC battery; a fifth lower switch connected between the other end of the second coil and the negative terminal of the DC battery; a sixth upper switch connected between the other end of the third coil and the positive terminal of the DC battery; and a sixth lower switch connected between the other end of the third coil and the negative terminal of the DC battery. A changeover switch for switching the connection between one end of the first coil and one end of the third coil and a single-phase voltage source on and off, A drive circuit that controls the driving of the primary inverter and the secondary inverter, The system includes a control unit that controls the drive of the three-phase motor via the aforementioned drive circuit, The control unit comprises a motor drive control unit that controls the rotational speed of the rotor of the three-phase motor, and a battery charge control unit that controls the charging of the DC battery via the three-phase motor from the single-phase voltage source. When controlling the rotational speed, the changeover switch is turned off to activate the motor drive control unit, and when charging the DC battery, the changeover switch is turned on to activate the battery charge control unit. Power converter.

2. When charging the DC battery, the battery charging control unit stops the operation of the first upper switch and the first lower switch, connects one end of the first coil to one output of the single-phase voltage source, stops the operation of the third upper switch and the third lower switch, connects one end of the third coil to the other output of the single-phase voltage source, and controls the operation of the fourth upper switch, the fourth lower switch, the sixth upper switch, and the sixth lower switch so that the voltage supplied from the single-phase voltage source to the DC battery becomes the target voltage. The power conversion device according to claim 1.

3. The battery charging control unit controls the operation of the second upper switch, the second lower switch, the fifth upper switch, and the fifth lower switch during charging of the DC battery, so that the second coil absorbs pulsating power from the power supplied to the DC battery from the single-phase voltage source. The power conversion device according to claim 2.

4. The battery charging control unit monitors the input voltage from the single-phase voltage source and controls the current in the second coil to be generated at the same frequency as the input voltage and with a phase lag of π / 4 from the phase of the input voltage. The power conversion device according to claim 3.

5. The battery charging control unit controls the amplitude of the current in the second coil so that it is determined based on the inductance of the second coil and the rated power of the DC battery. The power conversion device according to claim 3 or 4.

6. The battery charging control unit controls the operation of the fourth upper switch, the fourth lower switch, the sixth upper switch, and the sixth lower switch so that the currents in the first coil and the third coil have waveforms synchronized with the input voltage from the single-phase voltage source when charging the DC battery. The power conversion device according to claim 2.

7. A three-phase motor having a first coil, a second coil, a third coil, and a rotor, A primary inverter having: a first upper switch connected between one end of the first coil and the positive terminal of the DC battery; a first lower switch connected between one end of the first coil and the negative terminal of the DC battery; a second upper switch connected between one end of the second coil and the positive terminal of the DC battery; a second lower switch connected between one end of the second coil and the negative terminal of the DC battery; a third upper switch connected between one end of the third coil and the positive terminal of the DC battery; and a third lower switch connected between one end of the third coil and the negative terminal of the DC battery. A secondary inverter having: a fourth upper switch connected between the other end of the first coil and the positive terminal of the DC battery; a fourth lower switch connected between the other end of the first coil and the negative terminal of the DC battery; a fifth upper switch connected between the other end of the second coil and the positive terminal of the DC battery; a fifth lower switch connected between the other end of the second coil and the negative terminal of the DC battery; a sixth upper switch connected between the other end of the third coil and the positive terminal of the DC battery; and a sixth lower switch connected between the other end of the third coil and the negative terminal of the DC battery. A changeover switch for switching the connection between one end of the first coil and one end of the third coil and a single-phase voltage source on and off, A power conversion method using a drive circuit that controls the driving of the primary inverter and the secondary inverter, A first control is performed via the drive circuit to control the rotational speed of the rotor of the three-phase motor, The drive circuit performs a second control that controls the charging of the DC battery via the single-phase voltage source through the three-phase motor, In the first control, the changeover switch is turned off, and in the second control, the changeover switch is turned on. Power conversion method.

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